Experimental Study on Ground Interaction and Breakdown of Generic Transport Aircraft Wakes with Focus on Final Approach and Landing

大型运输机在最终进场和着陆过程中的尾涡特性对航空业和机场运营都有很大的影响。美国联邦航空管理局(FAA)和欧洲管制组织目前的努力旨在设计一种改进的尾涡咨询系统(WVAS)，以增加机场的容量，同时保持甚至超过当前的安全标准。因此，在国际项目重新分类(Recat)的框架内，工作正在进行中，以期在2020年前建立动态的成对飞机分离。尽管在过去的几年里做出了广泛的努力，但仍然非常需要研究来理解复杂的三维现象，尤其是发生在地面附近的现象。在欧洲网络WakeNET3的报告中，为了实现这些雄心勃勃的目标，明确制定了3个研究领域。在实验挑战方面，介绍了非线性飞机轨迹的研究，以及弯曲的涡流轨迹和近地面涡流行为的研究。目前，考虑飞机实际着陆的主题的研究是通过数值计算进行的，也是以使用激光光学测量技术(LIDAR)的全尺寸外场战役的形式进行的。在这些研究的框架内，还对地面措施(板块线)进行了调查，以促进靠近跑道的涡旋破裂。据申请人所知，目前文献中没有关于涡旋破裂的可比规模实验，包括着陆的实际影响。以前关于地面效应中的双涡系统的研究都是使用地面平行模型轨迹进行的。因此，这项研究的目标是对着陆飞机尾迹的破坏机制获得新的见解，并能够预测所涉及的二次不稳定的传播速度。为此，必须尽可能逼真地模拟实际着陆。重点研究了模型的轨迹和升力系数的时间演化，这需要模拟最终的进近，捕捉地面效果，以及模拟逼真的耀斑和触地。因此，本研究旨在对飞机着陆过程中和着陆后的全尺寸尾迹进行建模、仿真和预测。

The wake vortex characteristics of large transport aircraft on final approach and during touchdown are of large interest for the aircraft industry and to the same extent for airport operations. Current efforts of Federal Aviation Administration (FAA) and Eurocontrol aim at designing a modified Wake Vortex Advisory System (WVAS) to increase the capacity of airports, while maintaining or even exceeding current safety standards.Therefore, within the framework of the international project Re-Categorization (RECAT) work is in progress, in order to establish a dynamic pair-wise separation of aircraft by 2020. Despite extensive efforts over the last years, still there is a great need for research in order to understand the complex three-dimensional phenomena, which especially occur close to the ground. In the report of the European network WakeNET3 fields of research are clearly formulated to reach these ambitious goals. As for experimental challenges, the investigation of non-linear aircraft trajectories is stated, as well as curved vortex trajectories and the investigation of the vortex behavior near the ground.Current studies on the subject considering actual landings of an aircraft are conducted numerically, and also in form of full-scale field campaigns using laser-optical measurement techniques (LIDAR). Within the framework of these studies also ground based measures (plate lines) are investigated to promote vortex breakdown close to the runway.To the knowledge of the applicant, comparable scaled experiments regarding the vortex breakdown including the actual effects of landing are currently not represented in literature. Previous studies involving two-vortex systems in ground effect have been carried out using ground parallel model trajectories. Especially end effects, which are important in this context, have been excluded intentionally.Therefore, the goal of the proposed study is to achieve novel insights into the breakdown mechanisms of landing aircraft wakes, and to enable predictions of the propagation speed of the involved secondary instabilities. For this purpose the actual landing has to be simulated as realistic as possible. Special focus is put on the model trajectory and the temporal evolution of the lift coefficient, which requires to simulate the final approach, capturing the ground effect, as well as to simulate a realistic flare and touchdown. As a result this study intends to contribute to modeling, simulation and prediction of full-scale aircraft wakes during and after landing.